The present invention relates to an eyesight protection circuit of a TV set, and more particularly to an eyesight protection circuit by which the screen of a TV set goes blank, in case a TV viewer approaches into a predetermined distance from the TV set and the picture reappears when that viewer moves beyond that predetermined distance. The protection circuit has an infrared transmitter and receiver on the front of the TV set. Furthermore, this invention relates to an eyesight protection circuit by which the screen of a television set goes blank in case a viewer is positioned over a predetermined time within a predetermined distance from the screen.
The prior art to which the invention is directed includes the art of an eyesight protection circuit being of a type in which the screen of a TV set disappears, interpreting a TV viewer positioned within a predetermined distance from the TV set, when the signals uniformly amplified in the infrared receiver of the TV set are over a predetermined level.
However, there are some inevitable defects in this prior art; there may be a lot of deflections on the levels of the infrared receiver signls depending on reflecting materials, it is impossible to regulate the screen conditions and select a channel due to extinguishment of the screen even during the above regulation and selection operations, and there is the problem of a higher cost due to the requirement of respective infrared transmitter and receiver. See Korean Utility Model Reg. No. 30909 of May 2, 1986.
Furthermore, the other prior art to which the invention is directed includes the art indicating the approaches of a viewer by displaying a horizontal or a perpendicular bar on the screen in case the viewer or children approach near the TV set. See Korean Utility Model Application Filing No. 84-6720 of July 13, 1984; Early Publication No. 86-2086, Mar. 1, 1986; Early Publication Gazette No. 2. However, these screen variations arouse children's curiosity stimulating the children to approach near the screen of the TV set, therby not being able to obtain the desired result of protecting eyesight from the TV screen.
Accordingly, it is an object of the invention to provide an eyesight protection circuit for detecting a viewer within in a predetermined distance without errors to improve the effect of eyesight protections, by checking the existance of signal pulse of the infrared receiver, unlike the prior art comparing the signal levels thereof.
A further object of the invention is to lower the cost, by installing additionally only the infrared transmitter and substituting the remote control receiver already installed in the TV set for the infrared receiver.
These objects of this invention can be accomplished by letting infrared pulse signals, output from the infrared transmitter provided on the front of the TV set, be received on the remote control receiver already installed in the TV set afte they are reflected from the viewer positioned within a predetermined distance; discriminating a viewer positioned within a predetermined distance from the TV set while driving a monostable multivibrator by the above infrared pulse signals received on the remote control receiver; extinguishing the picture on the TV screen by inactivating the video amplifier when the monostable multivibrator is continuously drived over the predetermined time by the infrared pulse signals applied on it; and letting the picture reappear on the screen by operating the video amplifier when the monostable multivibrator is rested due to non-applying of the infrared pulse signals to it.